---
id: CVE-2025-39871
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  dmaengine: idxd: Remove improper idxd_free

  The call to idxd_free() introduces a duplicate put_device() leading to a
  reference count underflow:
  refcount_t: underflow; u…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  dmaengine: idxd: Remove improper idxd_free

  The call to idxd_free() introduces a duplicate put_device() leading to a
  reference count underflow:
  refcount_t: underflow; u…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-416
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 6.1.140, < 6.2'
  - 'linux_kernel >= 6.6.92, < 6.6.107'
  - 'linux_kernel >= 6.12.30, < 6.12.48'
  - 'linux_kernel >= 6.14.8, < 6.15'
  - 'linux_kernel >= 6.15.1, < 6.16.8'
  - linux_kernel = 6.15
  - linux_kernel = 6.17
patched:
  - linux_kernel 6.16.8
published: '2025-09-23'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T02:18:02.613'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-39871'
references:
  - url: 'https://git.kernel.org/stable/c/0e95ee7f532b21206fe3f1c4054002b0d21e3b9c'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/24414bbcb37e1af95190af36c21ae51d497e1a9e'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/da4fbc1488a4cec6748da685181ee4449a878dac'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/dd7a7e43269711d757fc260b0bbdf7138f75de11'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/f41c538881eec4dcf5961a242097d447f848cda6'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-019113.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-457936.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - cve.org
epss: 0.00154
epssPercentile: 0.04442
ingestedAt: '2026-09-08T15:33:26.996Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

dmaengine: idxd: Remove improper idxd_free

The call to idxd_free() introduces a duplicate put_device() leading to a
reference count underflow:
refcount_t: underflow; use-after-free.
WARNING: CPU: 15 PID: 4428 at lib/refcount.c:28 refcount_warn_saturate+0xbe/0x110
...
Call Trace:
 <TASK>
  idxd_remove+0xe4/0x120 [idxd]
  pci_device_remove+0x3f/0xb0
  device_release_driver_internal+0x197/0x200
  driver_detach+0x48/0x90
  bus_remove_driver+0x74/0xf0
  pci_unregister_driver+0x2e/0xb0
  idxd_exit_module+0x34/0x7a0 [idxd]
  __do_sys_delete_module.constprop.0+0x183/0x280
  do_syscall_64+0x54/0xd70
  entry_SYSCALL_64_after_hwframe+0x76/0x7e

The idxd_unregister_devices() which is invoked at the very beginning of
idxd_remove(), already takes care of the necessary put_device() through the
following call path:
idxd_unregister_devices() -> device_unregister() -> put_device()

In addition, when CONFIG_DEBUG_KOBJECT_RELEASE is enabled, put_device() may
trigger asynchronous cleanup via schedule_delayed_work(). If idxd_free() is
called immediately after, it can result in a use-after-free.

Remove the improper idxd_free() to avoid both the refcount underflow and
potential memory corruption during module unload.

## Affected

- `linux_kernel >= 6.1.140, < 6.2`
- `linux_kernel >= 6.6.92, < 6.6.107`
- `linux_kernel >= 6.12.30, < 6.12.48`
- `linux_kernel >= 6.14.8, < 6.15`
- `linux_kernel >= 6.15.1, < 6.16.8`
- `linux_kernel = 6.15`
- `linux_kernel = 6.17`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.16.8`